Coupled-Mode Analysis of a Metal-Coated Planar Waveguide with a Corrugated Long-Period Grating

The wavelength response of a metal-coated five-layer planar waveguide with a corrugated long-period grating is analyzed using the coupled-mode theory. The phase-matching characteristics between the core mode and the cladding modes are discussed for the coating with different metals and the different thicknesses of the cladding layers. Numerical results demonstrate that the rejection bands for the TE and TM polarizations can be well separated when both top and bottom surfaces of the waveguide are coated with aluminum films and the thicknesses of the cladding layers are optimized.